Carlos De La Cruz (R) and John Lujan (R) are running in the Republican primary runoff for Texas' 35th Congressional District on May 26, 2026. Lujan and De La Cruz were the top two finishers in the March 3 Republican primary with 32.5% and 27.1% of the vote, respectively. They advanced to a runoff because neither received more than 50% of the vote.

The primary runoff is taking place in the context of redistricting that changed the district lines from those used in 2024. Incumbent Greg Casar (D) is running for re-election in the new 37th Congressional District. An Inside Elections with Nathan L. Gonzales analysis of Texas' 2025 redistricting said of the 2026 version of the 35th District that "it’s possible that Democrats could get over the hump here, though probably only in a blue wave election."

President Donald Trump (R) and Gov. Greg Abbott (R) endorsed different candidates in the primary. Trump endorsed De La Cruz and Abbott endorsed Lujan. Spectrum News' Eleanor Fitzgerald said, "the race for District 35 will once again pit the weight of Trump’s endorsement against that of Abbott’s in the May runoff."

De La Cruz is a U.S. Air Force veteran and the founder and owner of a kickboxing gym. De La Cruz is the brother of Rep. Monica De La Cruz (R). De La Cruz describes himself as a "proud Air Force veteran, small businessman, husband, father, and conservative Texan with deep San Antonio roots." De La Cruz says he is running "to be President Trump’s wingman in Congress and take down the radical leftists who are destroying America."

Lujan was elected to the Texas House of Representatives in 2021. Lujan says he is running "to take this fight to Washington. With Donald J. Trump as our president, we'll continue to secure our border, unleash American energy, defend our Christian values, and stop the liberal agenda that's eroding our freedoms." Lujan says he "represents the very best of San Antonio and will be a dedicated voice for its citizens in Congress."

As of March 2026, The Cook Political Report with Amy Walter, Inside Elections with Nathan L. Gonzales, and Larry J. Sabato's Crystal Ball each rated the general election Likely Republican.